This study investiages the relationship between the Fridays for Future climate protest movement in Germany and citizen political behavior. In 2019, crowds of young protesters, mostly under voting age, skipped school to demand immediate climate action. Exploiting cell phone-based mobility data and hand-collected information on nearly 4,000 climate protests, a highly disaggregated measure of protest participation is created. The results show that Green Party vote shares increased more in counties with higher protest participation. Nonrandom protest participation is adressed using various empirical strategies. Empirical evidence indicates three mechanisms: reverse intergenerational transmission of pro-environmental attitudes from children to parents, stronger climate-related social media presence by Green Party politicians, and increased local media coverage of environmental issues. These findings suggest that youth environmental protests can drive societal change toward overcoming the climate crisis.